In the three decades between 1942 and 1972, American medical researchers conducted a series of experiments in which they deliberately infected human subjects with hepatitis. Attempts to develop animal models of viral hepatitis repeatedly failed and scientists resorted to human experiments to advance knowledge about the disease and the viral strains causing it. Their subjects-several thousand in all--were prison inmates, conscientious objectors, mental patients and institutionalized children. The federal government sponsored the studies, largely through the Army Epidemiology Board (AEB)-which become the Armed Forces Epidemiology Board (AFEB) in 1949. Institutions that managed prospective subjects actively cooperated in recruiting research participants. This included, in the case of conscientious objectors, both the Selective Service System and the coalition of historic peace churches that, during World War II, ran Civilian Public Service (CPS) camps. During the 1940s and 1950s, few argued that the experiments were morally unacceptable. But the climate supporting these and other hazardous medical experiments changed dramatically by the mid- 1960s. The hepatitis studies ended in the early 1970s as scientists and their sponsors confronted a newly established regulatory system and dramatically different sensibilities about human research. This project explores the conduct of the human hepatitis experiments and the social conditions and moral constructions that first enabled and then curtailed disease- inflicting human research in America. It draws on unusually rich and previously unexamined archival records. These documents allow me to examine in detail the actions and motivations of scientists, their subjects, and institutional leaders who made human experimentation possible. The book from the project will clarify how networks of social actors negotiate what levels of risk to human subjects are justifiable. It will provide vivid documentation of how historical events and shifts in the cultural context impinged on assessments of what constitutes acceptable human research.